U.S. patent number 5,756,900 [Application Number 08/788,296] was granted by the patent office on 1998-05-26 for pressure sensing apparatus.
This patent grant is currently assigned to Act Engineering Co., Ltd., Tasco Japan Co., Ltd.. Invention is credited to Nobuyuki Arie, Tomiki Ogi.
United States Patent |
5,756,900 |
Arie , et al. |
May 26, 1998 |
Pressure sensing apparatus
Abstract
There is provided a pressure sensing apparatus that does not
trap any fluid within its flow path and has a simple construction
so that it can be manufactured at reduced cost and has a diaphragm
that operates stably. Such a pressure sensing apparatus comprises a
sensor holder 21 having a flow path 22 arranged therein and
provided with a flat surface area 25 and a sensor receiving hole 23
cut from the outer periphery of the sensor holder to the flat
surface area 25 of the flow path 25. The apparatus also comprises a
diaphragm 24 that is level with the flat surface area 25 and has an
even thickness. A pressure sensor 31 arranged in the sensor
receiving hole 23. Since a pressure sensing apparatus having a
configuration as described above does not have any recess that can
trap fluid within the flow path 22, it does not degrade the purity
and cleanliness of the fluid running therethrough, if it is
connected to a piping system for fluid that requires purging.
Additionally, the fluid running through the flow path 22 of the
sensor holder 21 does not produce turbulences because of the
streamlined profile of the flow path 22 and, since the diaphragm 24
is integral with the sensor holder, no operation is required to fit
the diaphragm 24 to the sensor holder 21 and hermetically seal the
sensor holder 21 at the connection of the diaphragm 24.
Inventors: |
Arie; Nobuyuki (Tokyo,
JP), Ogi; Tomiki (Sagamihara, JP) |
Assignee: |
Tasco Japan Co., Ltd. (Tokyo,
JP)
Act Engineering Co., Ltd. (Sagamihara, JP)
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Family
ID: |
18433222 |
Appl.
No.: |
08/788,296 |
Filed: |
January 24, 1997 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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341951 |
Nov 16, 1994 |
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Foreign Application Priority Data
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Dec 28, 1993 [JP] |
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5-353787 |
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Current U.S.
Class: |
73/756 |
Current CPC
Class: |
G01L
19/0023 (20130101); G01L 9/0002 (20130101) |
Current International
Class: |
G01L
9/00 (20060101); G01L 19/00 (20060101); G01L
007/00 (); G01L 009/00 () |
Field of
Search: |
;73/756,861.47,861.62,861.63 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Oen; William L.
Attorney, Agent or Firm: Jacobson, Price, Holman &
Stern, PLLC
Parent Case Text
This is a continuation of application Ser. No. 08/341,951, filed
Nov. 16, 1994 which was abandoned upon the filing hereof.
Claims
What is claimed is:
1. A pressure sensing apparatus comprising a sensor holder
including a unitary body having a smooth flow path running
therethrough and a pressure sensor arranged in the body
characterized in that at least part of an inner surface of the flow
path includes a continuous flat surface area directed along the
flow path, said body including a sensor receiving hole formed from
an outer surface toward the flat surface area and forming a
diaphragm unitary with the body, said diaphragm having a constant
thickness extending between the flat surface area of the flow path
and an inner end of the sensor receiving hole, said diaphragm
having an inner surface level and continuous with the flat surface
area of the flow path thereby eliminating any material trapping
recess in the flow path to enable smooth unimpeded flow through the
flow path, said sensor being positioned ins aid sensor receiving
hole and associated with said diaphragm.
2. A pressure sensing apparatus according to claim 1, wherein the
flow path running through the sensor holder has a polygonal cross
section having said flat surface area as part of its inner
circumference.
3. A pressure sensing apparatus according to claim 1, wherein the
flow path running through the sensor holder has an arcuate cross
section having said flat surface area as part of its inner
circumference.
4. A holder for a pressure sensing apparatus comprising a body
having a flow path for pressurized fluid extending therethrough,
said flow path being defined by a longitudinally continuous smooth
inner peripheral surface, a portion of said continuous longitudinal
surface being flat throughout its length, said body including a
bore extending radially inwardly from an outer surface and
terminating in a bottom surface adjacent the surface of the flat
portion of said flow path, said bottom surface of the bore being
aligned with the continuous flat portion of the flow path and
adjacent thereto to define a diaphragm of equal thickness
throughout the bottom surface of the bore, said diaphragm being
unitary with the body and completely isolating the bore from the
flow path, said bore adapted to receive a pressure sensitive
apparatus for monitoring the fluid pressure passing through the
flow path, said smooth inner surface of the flow path eliminating
recesses capable of trapping fluid flowing through the flow path,
enabling smooth, unimpeded flow through the flow path and enabling
the diaphragm to be formed integral with the body by forming the
bore to accurately define the thickness of the diaphragm.
5. A pressure sensing apparatus comprising a sensor holder having a
smooth flow path running therethrough and a pressure sensor
arranged in the sensor holder characterized in that at least part
of an inner surface of the flow path includes a continuous flat
surface area directed along the flow path, said sensor holder
including a sensor receiving hole formed from an outer surface
toward the flat surface area and forming a diaphragm having an even
constant thickness extending between the flat surface area of the
flow path and throughout an inner end of the sensor receive hole
thereby isolating the flow path from the sensor receiving hole,
said diaphragm having an inner surface level with and forming a
continuation of the flat surface area of the flow path thereby
eliminating any material trapping recess in communication with the
flow path to enable smooth unimpeded flow through the flow path,
said sensor being positioned in said sensor receiving hole and
associated with said diaphragm.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a pressure sensing apparatus and, more
particularly, it relates to an improvement on a pressure sensing
apparatus to be fitted to a fluid piping system.
2. Prior Art
Pressure sensors designed for pressure control and flow rate
control are mostly realized by combining a diaphragm and a device
for translating changes in the pressure into those device in the
electric resistance or capacitance.
Pressure sensors of the above-identified type are popularly used
because they are small, have a simple mechanical construction and
comprises only small movable components.
It is well known that pressure sensors are favorably installed in
piping systems for supplying atmospheric and purging gases in the
semiconductor industry where a suitable environment needs to be
established for the manufacture of devices.
FIGS. 4 and 5 schematically illustrate a piping system provided
with a pressure sensor. Referring to FIG. 4, a gas source 1 and a
gas consuming installation 2 are connected with each other by way
of a primary-side gas feeding path 3, a secondary-side gas feeding
path 4 and a sensor holder 5 disposed between the paths.
As shown in FIG. 5, the sensor holder 5 is provided with a flow
path 6 having a circular cross section, a sensor receiving hole 7
also having a circular cross section and arranged perpendicular to
the flow path 6, a diaphragm 8 arranged at the crossing of the path
6 and the hole 7 and a casing 9 arranged on a lateral side of the
holder 5 where the sensor receiving hole 7 has an end thereof.
Referring again to FIG. 4, a pressure sensor 11 comprising a strain
gauge as a principal component thereof is placed in the sensor
receiving hole 7 of the sensor holder 5. The arrangement of the
pressure sensor 11 in the sensor receiving hole is more clearly
shown in FIG. 5.
As shown in FIG. 4, the pressure sensor 11 is provided with an
indicator 12 comprising an amplifier, display and other
components.
As gas is fed to the consuming installation 2 from the gas source 1
by way of the primary-side gas feeding path 3, the sensor holder 5
and the secondary-side gas feeding path 4, the diaphragm 8 is
deformed under the gas pressure.
Then, the pressure sensor 11 fitted to the sensor holder 5 detects
the strain generated in the diaphragm 8 under gas pressure and
causes the indicator 12 to display the gas pressure that has given
rise to strain so that the operator of the piping system can check
and see if gas pressure is found within a determined range.
(Problems to be solved by the Invention) A known pressure sensing
apparatus having a configuration as described above, however, is
accompanied by the following problems that are attributable to the
construction of the sensor holder 5.
(Problem 1)
Firstly, since the flow path 6 has a circular or curved peripheral
surface and the diaphragm 8 has a bottom surface, it presents a a
recess 10 as shown in FIG. 5 that traps gas there and prevents it
from flowing away.
Any gas trapped in the recess can contaminate the atmospheric gas
passing through the piping system and degrade the purity of the gas
to adversely and vitally affect the quality of the final
products.
(Problem 2)
Secondly, since the flow path 6 has a circular cross section, it is
highly difficult to form a diaphragm 8 integrally with a sensor
holder 5 that can be snugly placed in position.
Inevitably, the diaphragm 8 and the sensor holder 5 need to be
prepared separately and subsequently assembled together. This means
that a large number of steps are required for manufacturing the
components of the pressure sensing apparatus, assembling them and
sealing the manufactured apparatus to consequently push up the
manufacturing cost of the the apparatus.
(Problem 3)
Finally, since the flow path 6 has a recess 10 at an important
position (located near the bottom of the diaphragm 8) that
interferes with a smooth flow of gas, it is difficult for the
diaphragm 8 to operate stably and errors may inevitably be involved
in the pressure sensing operation of the apparatus.
These and other problems are commonly observed in pressure sensing
apparatuses that are installed in piping systems for corrosive
fluid (gas or liquid) or readily solidifying liquid.
(Object of the Invention)
In view of the above-identified technological problems, it is
therefore an object of the present invention to provide an improved
pressure sensing apparatus that does not trap any fluid in the flow
path of the apparatus while it comprises a simply configured
diaphragm that operates stably and, at the same time, allows to
reduce the overall cost of the apparatus.
SUMMARY OF THE INVENTION
According to the invention, the above object of the invention is
achieved by providing a pressure sensing apparatus comprising a
sensor holder having a flow path running therethrough and a
pressure sensor arranged in the sensor holder characterized in that
the sensor holder has on at least part of the inner surface of the
flow path a flat surface area directed along the flow path and a
sensor receiving hole formed from its outer surface toward the flat
surface area, that a diaphragm having an even thickness is disposed
between the flat surface area of the flow path and the bottom of
the sensor receiving hole, the inner surface of the diaphragm being
level with the flat surface area of the flow path, and that the
pressure sensor is disposed in the sensor receiving hole of the
sensor holder.
The flow path running through the sensor holder preferably has a
polygonal cross section or an arcuate cross section having a
straight line as part of the circumference.
(Function)
A pressure sensing apparatus according to the invention is designed
to be installed in a piping system for fluid.
Once the pressure sensing apparatus is installed in position, the
inner surface of the flow path of the sensor holder is subjected to
the pressure of the fluid running therethrough and through the
piping system to produce a strain therein as a function of the
fluid pressure, which is detected by the pressure sensor arranged
in the sensor receiving hole of the sensor holder.
Since the inner surface of the diaphragm is level with the flat
surface area of the flow path of the pressure sensing apparatus,
the flow path of the apparatus does not present any recess that may
adversely affect the flow of liquid in the apparatus Since the flow
path does not have any recess thereon, fluid can flow smoothly
through the flow path of the sensor holder so that no fluid may be
trapped within the flow path to adversely affect the operation of
purging the inside and consequently the diaphragm operates stably
under the pressure of the fluid running through the flow path.
Now, the present invention will be described in greater detail by
referring to the accompanying drawings that illustrate preferred
embodiments of the invention .
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side view side view, partly shown in cross section, of
a preferred embodiment of pressure sensing apparatus according to
the invention,
FIG. 2 is a sectional front view of the embodiment of FIG. 1,
FIG. 3 is a sectional front view of another preferred embodiment of
pressure sensing apparatus according to the invention,
FIG. 4 is a schematic block diagram of a piping system comprising a
conventional pressure sensing apparatus, and
FIG. 5 is a sectional front view of the pressure sensing apparatus
of FIG. 4.
DETAILED DESCRIPTION OF THE INVENTION
FIGS. 1 through 3 illustrate preferred embodiments of the
invention.
In FIGS. 1 through 3, reference numerals 21, 31, and 41
respectively denote a sensor holder, a pressure sensor and an
indicator.
The sensor holder 21 is made of metal or hardened synthetic resin.
A typical example of materials that can be used for the sensor
holder 21 is stainless steel (SUS316L).
When the sensor holder 21 is made of metal, it comprises a flow
path 22, a sensor receiving hole 23, a diaphragm 24 and other
components that are formed by means of metal molding and/or
machining (including the use of a wire cutter) and/or electric
machining (including electric discharge machining).
The flow path 22 running through the sensor holder 21 from a
lateral end to the opposite end thereof has quadrangular cross
section as shown in FIG. 2 or an arcuate cross section as
illustrated in FIG. 3. In other words, the flow path 22 has a flat
surface area 25 running longitudinally as part of the peripheral
surface thereof.
It is to be noted that the only requirement for the flow path 22 is
that it has a flat surface area 25 and, therefore, its cross
section may be other than quadrangular or arcuate and may
alternatively be triangular or pentagular.
The sensor receiving hole 23 is cut into the sensor holder 21 from
the outer surface of the latter until it gets into the flat surface
area 25.
The sensor receiving hole 23 may have a circular or polygonal cross
section but normally it has a circular or quadrangular cross
section.
The diaphragm 24 is formed in the sensor holder 21 simultaneously
with the sensor receiving hole 23.
The diaphragm 24 has an even thickness as the bottom plane of the
sensor receiving hole 23 is level with the flat surface area 25 of
the flow path 22 and consequently the inner surface of the
diaphragm 24 is level with the flat surface area 25.
The sensor holder 21 is provided on the outer periphery at the
opposite ends of the flow path thereof with respective threaded
sections 26 and 27 and on the outer periphery of the projection
thereof where the sensor receiving hole 23 is formed with a
threaded section 28 for engagedly receiving the casing.
The pressure sensor 31 may be of any known mechanical, electric or
electronic type or a composite type of any combination thereof.
More specifically, the pressure sensor 31 may be of a strain type,
semiconductor strain resistance type, a capacitance type or a force
balancing transmitter type.
If, for example, the pressure sensor 31 is of a semiconductor
strain-resistance, it comprises a sensing device 32 having a strain
gauge and ICs as components thereof and arranged in the sensor
receiving hole 23 of the sensor holder 21 and an output section
(electric arrangement) 33 electrically connected to the sensing
device 32 and fitted to the threaded section 28 of the sensor
holder 21.
The indicator 41 is also of a known type and comprises an
amplifying section, a display section and other components.
The indicator 41 is electrically connected to the output section 33
of the pressure sensor 31.
A pressure sensing apparatus according to the invention and having
a configuration as described above is fitted to piping system by
means of the threaded sections 26, 27.
Once the apparatus is fitted to a piping system and high pressure
gas is made to flow through the piping system, the diaphragm 24 of
the apparatus is strained as it is subjected to the high pressure
of the gas running through the flow path 22 of the sensor holder
21.
The strain that represents the pressure of the gas running through
the piping system is detected by the sensing device 32 of the
pressure sensor 31 arranged in the sensor receiving hole 23 of the
sensor holder 21 and the electric signal representing the pressure
and generated in the sensing device 32 is transmitted to the
indicator 41 by way of the 8k output section 33 so that the
operator can constantly monitor the gas pressure of the piping
system by watching the indicator 41.
A pressure sensing apparatus according to the invention does not
have any recess on the inner surface of the low path 22 of the
sensor holder 21 that can trap trap gas and adversely affect the
operation of the piping system.
Therefore, if the piping system is used to transport a material
gas, then, purged by a flow of a purging gas and thereafter used to
transport another material gas, the latter material gas is kept
pure and clean because no former material gas can can be trapped in
the flow path 22 of the sensor holder 21.
Additionally, since gas flows smoothly through the flow path 22 of
the sensor holder 21, the diaphragm 24 operates stably without
producing turbulences.
A pressure sensing apparatus according to the invention can be used
to detect the pressure of the liquid running through a piping
system.
While a strain type sensor holder 21 is described above for a
pressure sensing apparatus according to the invention, an elbow
type, T-type, cross type or any other type sensor holder may
alternatively be used for the purpose of the invention. If the
sensor holder is of a T-type or cross type, it may additionally
operate as a joint for connecting pipes.
(Advantageous Features)
A pressure sensing apparatus according to the invention has the
following features.
(Feature 1)
Since the flow path of the sensor holder of the apparatus has a
flat surface area and inner surface of the diaphragm is level with
the flat surface area, it does not produce any recess that can trap
fluid within the flow path. Thus, when the pressure sensing
apparatus is connected to a piping system that requires purging
operation in order to clean the inside of the pipes of the system,
the use of the apparatus does not degrade the purity and
cleanliness of the fluid running through the system.
(Feature 2)
Since the diaphragm of the pressure sensing apparatus is formed
simultaneously with the sensor receiving hole, the former can be
processed accurately without difficulty. In particular, since the
diaphragm is integral with the sensor holder, no operation is
required to fit the diaphragm to the sensor holder and hermetically
seal the sensor holder at the connection of the diaphragm. Thus,
the pressure sensing apparatus can be manufactured at the reduced
cost.
(Feature 3)
Since no recess is formed in the vital area (the bottom side of the
diaphragm) of the flow path of the sensor holder and any fluid can
smoothly run through the flow path, the diaphragm can operate
stably and accurately. Thus, the pressure sensing apparatus can
detect the pressure of the fluid running therethrough with a
minimum error level.
* * * * *